Just after 9 a.m. CDT, as Chief Justice John Roberts began to wind in to his summary of the Supreme Court’s landmark health-care opinion, he could hardly suspect that some in the media already were misreporting it.

Indeed, as Roberts was electrifying the assembly of lawyers, reporters, political figures and tourists in the high-ceilinged court chamber, journalists from CNN and Fox News Channel were already reporting — incorrectly — that the justices had struck down the individual mandate, the linchpin of the Affordable Care Act.

In fact, the mandate, which requires virtually all Americans to buy health insurance, had been upheld — albeit under an alternate theory than the main one put forward by Obama administration lawyers.

In an apology, CNN said it “regrets that it didn’t wait to report out the full and complete opinion regarding the mandate.’’

Fox, however, was unrepentant. According to the Associated Press, Michael Clemente, Fox executive vice president of news and editorial, said: “We gave our viewers the news as it happened … Fox reported the facts, as they came in.’’

Among the viewers initially taken in by the flub: President Barak Obama. He’d seen the bad news flash across TV screens in a room adjacent the Oval Office. It took White House general counsel Kathy Ruemmler to set him straight.

How could so many media outlets get such a momentous decision so wrong?

Not to let the misreporting journalists off the hook too easily, but part of the explanation is the disconnect between the court’s lengthy, intellectually challenging recitation of the case and the media’s laser focus on speed reporting.

Roberts started in by explaining how the mandate could not be sustained under the Constitution’s commerce clause, which limits congressional regulatory power to matters of interstate commerce. The Constitution, Roberts said, does not give Congress the right to regulate “inactivity’’ — the failure to buy a health insurance policy.

“Inactivity’’ was the backbone of the conservative argument for striking down the health-care law. So, clearly, Roberts was drinking their Kool-Aid . . . wasn’t he?

But Roberts then did the legal equivalent of jamming on the brakes of a car barreling down the highway at 80, spinning it into reverse as he upheld the mandate as a legitimate use of congressional taxing power.

The court — indeed all of Washington and the entire nation — was held breathless by the pivot.

CNN and Fox News, of course, corrected themselves as soon as their reporters, who received the 180-plus page opinion just after Roberts began his delivery, read far enough into it to realize their mistakes.

The episode brought to mind the journalistic chaos of December 2000 when journalists struggled to decipher the equally lengthy and complicated opinion in Bush v. Gore, which ultimately awarded the neck-and-neck 2000 presidential contest to George W. Bush.

On that night, on-air reporters fumbled through the opinion and offered running commentary of what they thought it concluded as they turned page after page.

It took news organizations the better part of an hour to figure out that Bush was the winner and former Vice President Al Gore the loser.